News Excerpt:

The dark energy content of the universe, based on theory, is wildly off the mark.

About Dark energy:

• Scientists believe that dark energy exists around us, composing almost 70% of the universe.
• Dark energy dictates the rate at which space expands. 
• From this, we can estimate how much dark energy is present in any space volume by considering the universe's size and age. 
• The universe is wider than billions of lightyears and older than 10 billion years, so the dark energy is as dilute as one sugar crystal in a cubic kilometre.
• Three unavoidable quantities behave exactly like dark energy - 
• The weight of the vacuum: 
• Einstein realised that space supplied its own energy and that it was spread uniformly, i.e. an energy that was a “cosmological constant”. 
• Back then, physicists believed that the universe, instead of expanding, stayed still. 
• So, in his equations, Einstein cancelled the cosmological constant against the energy of matter. 
• But when he soon learnt from astronomer Edwin Hubble that the universe is expanding, he rued the missed opportunity to forecast this observation, calling it his “biggest blunder”.
• Zero-point energy: 
• According to Heisenberg’s uncertainty principle of quantum mechanics, any physical system has a minimum positive energy.
• This is also true of quantum fields that source elementary particles such as electrons and photons (like sugarcane sources sugar cubes). 
• These fields fill space, thus furnishing energy at every point in the universe.
• Field potentials: 
• All fields have kinetic energy, but specific fields with no quantum spin, such as the Higgs field (which sources the Higgs boson), also have potential energies. 
• They also contribute energy to every point in the universe.

What is the Cosmological Constant Problem?

• The cosmological constant is a macroscopic parameter that controls the Universe's large-scale structure. 
• All observations to date have shown that it is very small. However, our modern microscopic theory of particle physics and gravity suggests that the cosmological constant should be very large. 
• This discrepancy between theoretical expectation and empirical observation constitutes the cosmological constant problem.

About the fine-tuning issue:

• The cosmological constant is unknown and appears to be fine-tuned over a breathtaking 122 decimal places. That is the core issue of the problem.